Synchronously improved fatigue strength and fatigue crack growth resistance in twinning-induced plasticity steels

The tensile, high-cycle fatigue (HCF) and fatigue crack growth (FCG) rate tests of Fe-30Mn-0.9C and Fe-30Mn-0.3C twinning-induced plasticity (TWIP) steels were performed. Meanwhile, the corresponding surface damages, fatigue fracture morphologies and microstructure evolutions were also investigated. It is detected that both the fatigue strength and FCG resistance of Fe-30Mn-0.9C steel are higher than those of Fe-30Mn-0.3C steel, because Fe-30Mn-0.9C steel possesses higher yield strength, plasticity and slip planarity than Fe-30Mn-0.3C steel. Furthermore, it is proposed that, for the Fe-Mn-C TWIP steel, increasing the C content to enhance the short range order (SRO) would lead to the synchronous increment in the fatigue strength and FCG resistance. This study may have a certain guiding significance for the selection of materials to against fatigue fracture.